Method of and apparatus for bending wooden sheets



A. ELMENDORF.

METHOU OF AND APPARATUS FOR BENDING wooosn sums.

APPLICATION FILED AUG- IB. 1921.

1,409,689. Patented Mar. 14, 1922.

2 SHEETS-SHEET I APPLICATION FILED AUG. 18, 1921 UNITEID- "STATES ARMIN ELMENDORF, O F CHICAGO ILLINOIS.

ll/IETHOD OF AND APPARATUS FOR BENDING WOODEN SHEETS.

Specification of Letters Patent.

Patented Mar. 14:, 1922.

Application filed. August 18, 1921. Serial No. 498,289.

have invented a certain new and useful im provement in Methods of and Apparatus for Bending Wooden Sheets, and declare the following to be a full, clear, and exact description of the same. such as will enable others skilled in the art to which it pertains to make and use the same. reference being had to the accompanying drawings which form a part of this specification.

In order to bend wood sharply as, for example, to produce a comparatively sharp right angle corner, it is necessary that the wood be first softenech This applies both to sheets made of a single layer and to plywood sheets or panels. The sottening can be'produced by moisture or by a combination of moisture and heat, both moisture and a comparatively high degree of heat being necessary to make the process rapid enough for commercial purposes. So far as I am aware, the practice heretofore has been to steam or otherwise moisten and heat an entire sheet in order to permit a sharp bend to be made therein.' -Afterwards the entire sheet must again be dried. This wetting of the entire sheet simply for the purpose of making a sharp bend along a line extending across the same therefore necessitates a prolonged drying operation which not only wastes time but is otherwise costly. A far greater objection, however. results in many instances from the wetting of an entire sheet. namely the warping effect on the wood which causes the wood to become distorted.

One of the objects of the present invention is to produce a simple and novel method of making a sharp bend in a sheet or panel made of one or more layers, whereby the moisture is applied only along a narrow strip traversed by the line along which the bend is to be made, so that the main body of the sheet will not be in any way affected.

A further object of the present invention is'to produce a simple and novel method of moistening and heating a com aratively narrow strip extending across a s. set, so as to soften such strip without affecting the remainder of the sheet. A further object of the present invention is to produce a simple and novel method oi? forming a sharp bend in a wooden-sheet in such a manner that the bend may be formed and the work as a whole be left in a dry state by a single comparatively rapid manipulation or operation. 7

A further object of my invention is to produce a simple, novel and efficient machine for rapidly forming bends in wooden sheets and delivering the product in a dry state.

The various features of novelty whereby 'my invention is characterized will hereinafter be pointed out with particularity in the claims, but, for a full understanding of my nvention and of its objects and ad vantages, reference may be had to the following detailed description taken in con-- nection with the accompanying drawings, wherein:

Figurel is a front el'evation'of a simple machine by means of which my invention may be carried out; and

Figure 2 is a section taken approximately on line 22 of Fig. l, the watcrcontr0l ling valve being also shown in section.

My invention is capable of wide application. One of the important uses to which it may be put is the manufacture of shells or containers of polygonal cross section formed by bending a sheet of two-ply wood into the proper shape and then fastening the meeting edges together in any suitable way; and. for the sake of brevity, I shall. confine the detailed description to this .particular use.

Referring to the drawing, 1 represents a suitable frame which supports a horizontal bar 2 having a downwardly-facing corner The bar is shown as being approximately triangular in cross section and it is made hollow so as to provide for the admission of steam into the interior thereof; a suitable steam delivery pipe 4 and a discharge pipe 5 being connected to the respective ends of the bar for this purpose. Underneath the member 2, and parallel therewith,

is a vertically movable bar or pressure device 6 having a trough-shaped upper side 7 adapted to fit around the downwardlyproject-ing corner of the member 2 when the member 6 is raised.

It will be seen that when a piece of plywood, such as indicated at A, is slipped between the two bars and the lower bar is raised, the work will be engaged on the under- V shape inw'hich it contains a slight valley, a

small amount of water maybe. placed. in the valley and will remain in the bottom of the :vialley so that the wetting of the sheet will beconfined to the com iiaratively narrow 'fstrip in contact with-the corner'of the memher 2 while all the restiofthe sheet will remain dry. The water may be introduced into the val'leyof'thesh'eet in any convenient way. 11 the arrangement shown," I haveyprovrdeda single water pipe 8 the delivery end of whichfextends down through a vertical passageDht-about the middle of the bar heated surfaces of the bar 2 and having its temperature raised to about the boiling point, at which temperature it acts quickly to penetrate the wood and effect the softening thereof. If the upward pressure on the lower bar is continued, the gradual softening of the wood as the heated water penetrates the same will reduce its capacity to resist the bending stresses and it will be gradually bent from the condition illustrated in full lines in Fig. 2 to thatshown in dotted lines. When it reaches the condition shown in dotted lines it will have been bent to the shape of the lower side of the bar 2 and will lie in con tact with the lower converging faces 10 and,

11 of the bar. Assuming that the flow of water has been stopped when a sufiieient amount has been delivered to produce the desired degree ofsoftness in the worln'it will be seen that the damp corner in the work will be driedthrough contact with the hot bar and, if the moisture has spread somewhat away from; thecorner, the comparatively wide areas of contact between the work and the hot bar will insure dryness at all points, if the work is left in the machine long enough. Because of the small amount of water used, the evaporation of the same takes place very quickly.

The machine illustrated is designed to receive work at various lengths and therefore it may sometimes happen that some of the water will run out of the ends'of the valleys in the work and down into the trough of the lower bar. I have therefore provided the trough in the lower bar with a discharge pipe 12 through which any wasted water may es cape. -Warm air may be introduced through this pipe to accelerate the drying.

I prefer to arrange a series of wells in the top of the lower bar, there being, in the arrangement shown, a central well-13 opening down from the bottom of the trough and two other wells 1% and 15 opening down from the sides or slopes of the trough; all three wells being connected together attlie'bottombya transverse passage 16; By thisarrangement there is very little metal at anytime in engagement withthe under surface of the work},

r ihe machine may beprovided with adj ustable gauge airs 17 and 18, are illustrated lf a she'et is to be bentinto the formof a box of shell rectangu 'lar in section, 1e gauge 1"? will be set so the distance between the same and'the corner 3 is equal was width the, short side of the shellor box and the gauge 18 is-s'et so that the distance between the same andthe corflat sheet is placed in theimachine it will strikethe "auge 17, but, ifthefree or advance end'is lifted slightly it "may pass over the gauge l'T and travetover to the other gaugef a F1,

' The pressure bar 6 may beoperated in any suitable way. The machine which I have illustrated is oneadapted to be operated manually and I have therefore provided a treadle 19 fixed to a horizontal shaft 20 lying below and parallel with the bar 6; the bar 6 being connected to the treadle by means of a connecting rod 21 whose lower end is arranged close to the treadle shaft. Projecting in the opposite direction from the treadle shaft to that in which the'treadle extends are a pair of arms 22 provided with a heavy counterweight or counterweights 23 which may be adjusted lengthwise ofthe arms.

The parts are so proportioned'tl'iat the counterweights force the movablepressure bar upwardly with considerablepressure to effect the bending operation; these counterweights constituting a simple means for exerting a. continuous yielding" upward pressure on the work.

lVhen the operator places a piece of work of which two,- indi'eated'at V the wood progresses. The result is that the pressure on the work becomes progressively greater in proportion to the resistance offered by the work, so that when the bending movement has been completed, the pressure is great enough to insure that those portions of the sheet adjacent to the corner 3 will be pressed firmly against the converging sides of the upper bar and insure a sharply defined corner. The ratio between the pressure and the resistance may be made still greater the pressure bar rises by so positioning the center of gravity of the counterweights and the pivotal connection 24: between the connecting rod and the treadle, that the counterweights act through a gradually increasing leverage as the pressure bar rises. This is conveniently accomplished, as shown, by causing the horizontal distance between the axis of the shaft 20 and the pivotal axis v 24 to decrease as the pressure bar rises while the horizontal distance between the axis of the shaft 20 and the center of gravity of the counterweight increases as the counterweight descends.

The How of water may be controlled in any suitable way. In the arrangement shown, I have made the control automatic. To this end I have placed in the pipe 8 a valve device containing a needle valve 25 which may be adjusted so as to produce any desired flow of water when the valve is open. A spring 26 tends constantly to hold the valve open. Fixed. to the treadle shaft 20 is a radial arm 27 in position to engage with the upper end of the needle valve and force it down into a closed position whenever the treadle is up or, in other words, whenever the pressure bar has been moved to its upper limit. Consequently, when the operator places his foot on the treadle to open up the machine, he opens the needle valve and water immediately begins to flow upon the work when the latter is placed in the machine. The water continues to flow, in gradually reduced amounts, if desirechuntil the machine has completed the bending operation; whereupon the arm 27 forces the needle valve into its closing position and shuts off the supply of water.

It will thus be seen that all that the operator has to do is to put his foot on the treadle, place the work properly in the machine, and then remove his foot, the machine then performing its work automatically.

The time required. for drying the work is suflicient to enable the operator to place a piece of work into or shift the work in another machine,'so that no time need be lost in waiting for the work in a machine to dry.

' hile I have explained my invention by means of a simple and novel machine in which the invention may successfully be carried out, I do not desire to be limited to the specific machine illustrated, because my invention may be carried out by hand manipulations and by other forms of machines. Furthermore, while reference is herein made to sharp bends and sharp corners I do not mean by those terms bends or corners in which two surfaces meet in a single line, but rather bends or corners which bring two surfaces which lay in the same plane into two planes at an angle to each other.

I claim:

1. The method of bending a sheet of wood which consists in applying pressure to the sheet held horizontally to form a bend sufiicient to produce a slight valley, supplying water to the valley, and continuing the pressure and at the same time applying heat to the water until the bend has been completed.

2. The method of bending a sheet of wood which consists in applying pressure to the sheet held horizontally to form a bend sufiicient to produce a slight valley, supplying water to the valley, continuing the pressure and at the same time applying heat to the water until the bend has been completed, shutting off the water, and continuing the application of heat until the moistened portion of the wood has been dried.

3. The method of bending a sheet of wood which consists in applying pressure to the sheet while held horizontally so as to bend itsufiiciently to form a slight valley, introducing a small amount of water into the valley, and heating the water and continuing the pressure to complete the bending operation as the wood forming the bottom of the valley softens.

4. The method of bending a sheet of wood which consists in applying pressure to the sheet while held horizontally so as to bend it sufficiently to form a slight valley, introducing a small amount of water into the valley, heating the water and continuing the pressure to complete the bending operation as the wood forming the bottom of the valley softens, and thereafter continuing the application of heat and pressure until the water has evaporated and the dampened portion of the wood has become dry.

5. The steps in the method of bending a sheet of wood which consists in fiexin or bending the sheet sufiiciently to form a slight horizontal valley, placing water in the bot tom of the valley, and heating the water.

6. The method of bending a sheet of wood which consists in pressing it against a heated sharp corner in such a manner as to tend to bend 1taround sald corner and form a valley, deliverlng a small amount of Water into said valley, and continuing the bending pressure as the heat and moisture soften the sheet until the bending has been completed. 7 The method of bending a sheet of wood 7 which consists in placing it against a sharp heated corner, applying pressure on the op- 10 posite face of the sheet and on opposite sides ARMIN ELMENDORF, 

